1. Field of the Invention
The present invention relates to an ophthalmologic apparatus used in an eye clinic or the like and a control method for the ophthalmologic apparatus.
2. Description of the Related Art
As an ophthalmologic instrument, there is known a fundus camera for performing fundus imaging of an eye to be inspected.
When taking an image of a fundus by the fundus camera, it is necessary to align an imaging portion with a predetermined position with respect to the eye to be inspected. In order to perform this alignment, the following fundus camera is widely known. The fundus camera includes an alignment operation member such as a joystick, and the alignment operation member is operated (tilted, rotated, and the like) so that the imaging portion is moved up and down, front and back, and left and right.
In general, the alignment operation member for the fundus camera performs a rough operation in which the imaging portion is roughly moved in a case where rough alignment is sufficient such as the case of switching the imaging portion between left and right eyes. In addition, the alignment operation member has a mechanism capable of performing fine movement in which the imaging portion is precisely moved when fine alignment with the eye to be inspected is necessary.
In Japanese Patent Application Laid-Open No. 2001-037722, there is disclosed a structure in which a moving amount of the imaging portion per unit operation amount of the alignment operation member is changed in accordance with an alignment deviation amount between the eye to be inspected and the imaging portion. The alignment deviation amount is determined from a deviation between the center of a sighting scale S set in an anterior ocular segment image of the eye to be inspected and a position of an alignment visual target image T obtained from a cornea of the eye to be inspected. In this structure, the imaging portion is greatly moved if the alignment deviation amount is large, while the imaging portion is moved small if the alignment deviation amount is small, so as to improve alignment operability.
However, in the structure disclosed in Japanese Patent Application Laid-Open No. 2001-037722, no consideration is made for a case in which an alignment deviation amount between the eye to be inspected and the imaging portion cannot be detected. The case in which the alignment deviation amount cannot be detected is, specifically, a case in which the visual target image T to be obtained from the eye to be inspected cannot be detected because of blinking, insufficient eye opening, a small pupil, or the like.
It is needless to say that, if a position of the eye to be inspected cannot be detected, a feedback to the operation member cannot be performed, and hence improvement of operability cannot be expected. In other words, it is hitherto essential to detect a position of the eye to be inspected when performing alignment, and there is high possibility that uncomfortable operation feeling occurs depending on success or failure in the detection or on time necessary for the detection.